REG NASA-LLIS-1202-2002 Lessons Learned Vibration-Induced Failures of Electronic Component Leads as a Result of Improper Mechanical Packaging Design.pdf

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1、Lessons Learned Entry: 1202Lesson Info:a71 Lesson Number: 1202a71 Lesson Date: 2002-02-11a71 Submitting Organization: JSCa71 Submitted by: Robert Wm. CookeSubject: Vibration-Induced Failures of Electronic Component Leads as a Result of Improper Mechanical Packaging Design Description of Driving Even

2、t: A battery charger design was reported to have experienced catastrophic component failure during vibration testing, resulting in fractured and broken component leads of heatsink-mounted power devices. A photograph of the failed assembly (Fig. 1) clearly showed a pattern of damage consistent with r

3、epeated movement and flexure of the components. The primary cause of the unwanted movement was attributed to a design decision, in which the heatsink was allowed to “float“ with respect to the printed wiring assembly. A design change, which mechanically bonded the heatsink and the printed wiring ass

4、embly together, significantly reduced the incidence of component lead failures during vibration tests. A visual examination of sample components supplied to JSC suggested that the use of unapproved tooling and processes during the component lead forming process was a contributing factor to the obser

5、ved fractured and separated leads, with numerous sample components exhibiting leads with cracks (Fig. 2). Discussions with the vendor indicated that metallic tools (including a screwdriver) were employed to form the leads. Subsequent improvement in tooling and processes resulted in smoothly formed l

6、ead bends, without fractures or significant tooling marks. Lesson(s) Learned: Poor mechanical design and the use of unapproved workmanship practices in the manufacture of electronic systems, where components may be subjected to vibration-induced movement, will result in work fatigue of the leads to

7、the point of fracture and separation.Recommendation(s): Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The mechanical bonding of the heatsink to the printed wiring assembly results in a unitized structure, providing the components with the support n

8、ecessary to prevent the reported damage. The elimination of unapproved tooling and processes ensures that electronic components will not possess latent damage that would result in reduced reliability. Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorat

9、e(s): N/AAdditional Key Phrase(s): a71 Flight Equipmenta71 Hardwarea71 Parts Materials & ProcessesAdditional Info: Approval Info: a71 Approval Date: 2002-05-28a71 Approval Name: Ronald A. Montaguea71 Approval Organization: JSCa71 Approval Phone Number: 281-483-8576Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-